Method and apparatus for annealing strip



&199.472

May 7, 1940. R. J. WEAN METHOD AND APPARATUS FOR ANNEALING STRIP Filed Feb. 9, 1939 3 Sheets- Sheet 1 s n a o e F r `\,.N m M j 0 R r. m

//// l/l/l I/ l//l I I I I R. J. WEAN METHOD AND APPARATUS FOR ANNEALING STR Fie Feb. 9, 1939 May 7, 1940.

y 9 0. R. WEAN 2,99,472

METHOD AND APPARATUS FOR ANNEALING STRIP Filed Feb. 9, 1939 3 sheets -shet 3 ooooooooooq-o'ooodooooo Patented May 7, 1940 UNITED STATES PATENT OFFICE NIETHOD AND APPARATUS FOR ANNEALING STRIP Raymond J. Wean, War-ren, Ohio, assignorto The Wean Engineering Company, Inc., Warren, Ohio, a co'poration of Ohio Application February 9, 1939, Serial No. .255,429

4 Claims.

heretofore by placing them in annealing boxes and subjecting theboxes to heating in a conventional furnace or a furnace of the cover type. This method of processing is very slow and does not produce a uniform efiect throughout the mass of material being treated. Because of the time required for annealing by this method, the cost of the operation is quite high.

I have invented a novel method and apparatus for processing thin rolled material which is particularly adapted for the annealing of steel strip. In a preferred practice and embodiment of the invention, I pass the strip in strand form through a heating chamber provided with contact heatexchange drums, and cause the strip to traverse a path such that it wraps around the drums during its passage through the chamber. The strip may also be looped back and forth adjacent heatradiating means, thereby supplying further heat to the strip. After being brought to the desired temperature, the strip is fed continuously through a cooling chamber whereby to reduce the temperature of the strip gradually. The heating chamber and the cooling chamber are provided with a non-oxidizing atmosphere to protect the material from oxidation while at elevated temperature. The invention will be described in' detail herebelow by reference to the accompanying drawings illustrating a preferred constructlon and procedure. In the drawings:

Fig. 1 is a substantially central section taken ,longitudinally through an annealing apparatus comprising heating and cooling chambers in accordance with the invention;

Fig. la is a partial elevation of the top of the heating chamber;

Fig. 2 is a sectional view taken substantially along the line II-II of Fig. la;

Fig. 3 is a partial plan view of the cooling chamber with the top wall thereof removed; and

Figs. 4 and 4a taken together constitute a view similar to Fig. 1 showing a modification.

Referring now in detail to the drawings, and for the present to Figs. 1 through 3, the strip S to be annealed is delivered from any convenient source such as a coil suitab ly supported and is 'guided by a drum Il] into a heating chamber provided with contact heat-exchange drums l2. The strip enters the chamber through a, slot 3 in the bottom thereof between sealing rolls l4. The chamber comprises side walls, a bottom and a top composed of refractory material assembled within a frame made of structural members and sheathing plates.

As shown in Fig. la, the drums l2 are rotatably mounted on brackets |5 carried on the frame of the heating chamber. Ports formed in one of the side walls of the chamber, normally closed by removable covers !6, permit the insertion and removal of the drums l2. One of the side walls parallel` to the axes of the drums may be -provided with window-like openings provided with suitable closures, whereby the initial threading of the strip through the chamber and around the drums l2 may be facilitated.

The drums l2 may be of any desired Construction. One suitable form thereof is shown in detail in Fig. 2. Referring more particularly to the latter, a hearing casting 24 is carried on one of the brackets l5. The casting 24 has a seat 25 thereon for a stationary hearing race 26. A casting 21 mounted on a bracket l5 on the other side of the chamber is provided with a seat 28 for a stationary bearing race 29. The castings 25 and 21 have annular passages 30 therein for cooling fluid supplied thereto and exhausted therefrom through any suitable connections (not shown).

Eachof the heat-exchange drums |2 is preferably composed of a heat-resistant alloy and has trunnions 32 and 33 journaled in bearings 34 and 35, of which the stationary races 26 and 29 form parts. As shown in the drawings, these bearings are designed to permit axial removal of the drum on leftward movement thereof with the cover !6. Packing glands 36 and 31 close the spaces between the trunnions and the castings in which their supporting bearings are mounted.

A burner tube 38 extends into each drum through the trunnion 33 and is provided with ports 39. The burner is connected to and is supported on a fuel supply pipe 40 extending to a fuel air mixer (not shown). A packing gland closes the space between the trunnion 33 and the burner 38. 4

The trunnion 32 is provided With a refractory lining 42 constituting an exhaust passage for combustion gases discharged from the drum. An exhaust duct 43 having a lining similar to that shown at 42 is disposed adjacent the trunnion 32 and extends laterally thereirom to any suitable waste gas passage.

It will be apparent that when a-combustible mixture is supplied through the burner tubes 38 and ignited, the drums |2 will be heated to a relatively high temperature and that the strip S,

in traveling about the several drums successively, r

will be quickly heated to a corresponding temperature. It will be noted in Fig. 1 that the strip entering the chamber passes first around the drum next above the lowest, thence around the lowest drum, the top-most drum and the drum therebelow. By training the strip around the drums in this manner, a large arc of contact between the strip and the drums is maintained. The temperature to which the strip is heated by contact with the drums may be controlled by varying the speed at which strip is fed through the chamber as well as by controlling the supply of fuel to the burner tubes 38 of the several drums.

A deoxidizing atmosphere is supplied to the chamber Il through an inlet indicated at 44, to protect the strip from excessively rapid oxidation while at elevated temperature.

After traversing the contact heat-exchange drums successively, the strip leaves the heating chamber through a slot 45 in the top thereof opening into an initial cooling chamber 46. i

The initial cooling chamber 46 is disposed above the heating chamber ll and extends laterally thereof. The chamber 46 communicates with the chamber II through a neck or duct 41 of reduced cross sectional area. Sealing rolls 48 engage the strip as it enters the chamber 46 and spaced guide drum 49 convey it therethrough. The drums 49 may be of any suitable material and, if desired, may be provided with scrapers (not shown) to remove any accretions which might be' picked up thereby from the strip and cause scratches in the surface of portions of the strip subsequently passing over the drums. The drums may be of an alloy which is resistant to high temperatures such as nichrome. Alternatively, the drums may be of softer material such as copper or Monel metal.

The drums 49 are preferably provided, throughout at least a portion of their circumference, with shrouds 50 of thermal insulation. These shrouds maintain the drums at an elevated temperature to which they are heated by contact with the strip emerging from the chamber ll, thus preventing excessively 'rapid cooling of the strip as it engages the drums and the objectionable buckling resulting therefrom. Between the drums 49, cooling tubes 5l are disposed. The tubes 5l are backed by thermal insulation 5I cooperating with theshrouds 50 to prevent excessively rapid cooling of the strip. Any suitable cooling fluid such as water may be circulated through the tubes 5! at a rate sufiicient to produce an initial reduction in the temperature of the strip from the maximum to which it was heated in the chamber ll. An inlet 52 for deoxidizing gas extends into the chamber 46.

A cooling chute or duct 53 extends downwardly from the chamber 46 and similar ducts 54 and 55 are disposed in succession therewith. Guide drums 56, 51, and 56 journaled in or adjacent the ends of the ducts convey strip successively therethrough to permit gradual cooling thereof. A deoxidizing gas inlet 59 is located at the top of the duct 54. The ducts 53, 54 and 55, as well as the chamber 46, are composed of sheet metal erocted on suitable frame members. with gastight joints. The end walls of the ducts are provided with thermal insulation to prevent cooling of the outer'edges of the strip at an excessively rapid rate since the loss of heat from the strip would otherwise be greater near the outer edges than adjacent the middle thereof. The ducts are provided with baflles 60. cooling tubes Bl are mounted in the upper end of the chute 53. By

circulating cooling fluid through the tubes 6l, the cooling of the strip initiated by the tubes 5! is continued. The tubes 5l and 6l, as shown in Figs. 4 and 5, are preferably of hair-pin or inverted V-shape and thus cause the cooling of the strip to commence adjacent the middle thereof as it approaches the tubes, finally extending to the edges. This avoids buckling which might result from an attempt to cool the strip simultaneously throughout its width, at one point in its travel.

The cooling of the strip continues as it passes through the ducts 53, 54, and 55 and when it finally emerges from the latter between scaling rolls 62, it has been reduced to a temperature at which atmospheric oxidation does not proceed rapidly and is, therefore, ready for re-coiling or for further immediate processing, e. g., stamping, coating, or the like.

Any suitable traction means may be employed for advancing the strip through the heating and cooling chambers. Since the heating drums are journaled on anti-friction bearings, a relatively low tension applied to the strip emerging from the cooling ducts will be suffisient to cause continued feeding of the strip. If the strip is being coiled, the coiler drive will be such as to effect the necessary tension. If the material is not being coiled, a pair of feeding pinch rolls may be provided to draw the strip through the annealing apparatus.

Figs. 4 and 4a illustrate a modification of the invention already described. In the modified form of the invention, a heating chamber 65 is provided with guide drums 66 and radiant tubes 61, in addition to the contact beat-exchange drums |2. The tubes 61 may be mounted in the heating chamber in any convenient manner and supplied with a combustible mixture whereby they are heated to radiant temperature and serve to deliver heat to the strand of the strip nearest them. This strand on becoming heated radiates heat to the adjacent strand and so on. It will be appreciated that the back-and-forth looping of the strip around the guide drums 66 adjacent the radiant tubes 61 causes the temperature of the various portions of the strip to be equalized whereby a high degree of uniformity is obtained in the finished product.

The parts of the apparatus shown in Figs 4 and 4a which have not been exp'essly referred to are similar to the corresponding parts of the previously described form of the invention and are -designated by the same reference numerals.

It will be apparent that the invention provides a method and apparatus whereby strip may be annealed much more rapidly and at a 'much lower cost than by the methods now being practiced. The apparatus shown is relatively simple in Construction and does not represent an excessive investment when the large Capacity thereof is considered. The process is continuous and all portions of the apparatus are fully utilized all the time, contributing to a high degree of emciency. The baflles in the cooling ducts prevent virgorous circulation of the atmosphere therein which might result from the fiue-like nature thereof.

Although I have illustrated and described but a preferred form and practice of the invention with a slight modification, it will be understood that changes in the Construction and procedure disclosed may be made without departing from the spirit ot the invention or the scope of appended clalms.

I claim:

1. In a. method of annealing metal strip the steps including advancing the strip in strand form, heating the strip to annealing temperature, and circulating cooling fluid thereadjacent along a v-shaped path, the vertex of the path being disposed substantially centrally of the strip and toward the direction from which it approaches.

2. .Apparatus for annealing metal strip comprising means for advancing strip in strand form, an imperforte cooling-fluid ?Conduit mounted adjacent the path of the strip, and connections for causing a flow of cooling fluid through the conduit, said conduit being of substantially V- shape and disposed with its vertex substantially centrally of the strip and toward the direction the 20 from which the strip approaches.

has been heated for anneaiing comprising a cooling duct through which the strip travels in strand form, guiding drums adjacent opposite ends of the duct over which the strip travels, and cooling means between said drums including imperforate V-shaped cooling-fluid pipes so disposed adjacent the path of the strip as to be eifective to start cooling of the strip at its middle and to cause the cooling to proceed progressively toward the edges of the strip as it moves past the pipes.

4. Apparatus for treating metallic strip which has been heated for annealing, comprising a cooling chamber, means for conducting strip therethrough in strand form, an imperforate V- shaped cooling tube in said chamber, the vertex of the tube being disposed substantially centrally of the strip and extending in a direction opposite that in which the strip travels, and connections for flowing cooling fluid through said tube.

RAYMOND J. WEAN.

GTI 

